Improvement of Engineering Properties of Expansive Soil Modified with Scoria

Abstract

Expansive soil is known for its high susceptibility to shear failure, unexpected differential settlement and experiencing low bearing capacity, which makes it an unsuitable soil for a variety of engineering uses. This soil is characterized by considerable volume changes due to seasonal variations and moisture content. Lightweight structures cannot exert the necessary counter load to overcome the swelling from expansive soil. Therefore, this study aims to evaluate the improvement in some engineering properties of expansive soil modified with scoria. Soil properties were collected from the field for laboratory analysis of Atterberg limit, unconfined compression strength (UCS), consolidation test, California Bearing Ratio and compaction characteristics following ASTM testing procedures. Mixing of scoria with expansive soil with different percentages decreases the free swell, liquid limit, plastic index, optimum moisture content and increases plastic limit and maximum dry density. Similarly, unconfined compression strength, CBR value and consolidation increased up to 20% of scoria mix; then, as the percentage of scoria increased beyond this value, reverse properties are observed. Analysis of the results shows a significant improvement of geotechnical properties of scoria-stabilized soil. The results revealed that 20% of scoria is the optimum percentage used for improving engineering properties of expansive soil.